Information processing device and controlling method

ABSTRACT

A processor determines a target value of a temperature of a processing unit included in the information processing system on the basis of the temperature of the processing unit when first power consumption indicates a relatively low power consumption by referring to correlation information that indicates a change in the first power consumption, which is a total sum of second power consumption of the processing unit and third power consumption of an air-conditioning machine included in the information processing system, with respect to a change in the temperature of the processing unit. Then, the processor outputs a control signal for controlling the air-conditioning machine on the basis of the target value.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication PCT/JP2012/058640 filed on Mar. 30, 2012 and designated theU.S., the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to an information processing device and acontrolling method.

BACKGROUND

With the progress in cloud services, power consumed by data centers,with an information processing system as a base, is expected tosignificantly increase in the future, and saving power in data centersis under study.

The power consumed by a data center includes power consumed byinformation technology (IT) devices such as a server, a network device,a storage device and the like, and that consumed by air-conditioningmachines for cooling down the IT devices and the like. The powerconsumed by the air-conditioning machines accounts for a largepercentage of the total power consumption. Accordingly, to save thepower in a data center, not only reductions in the power consumption ofIT devices but reductions in the power consumption of air-conditioningmachines, which account for a large percentage, are under study.

A large data center is provided in a robust building, and includesequipment such as a power-feeding system to cope with blackouts, anadvanced security system, and the like, and employs highly efficientair-conditioning machines that take into account an operatingenvironment of IT devices in many cases.

In the meantime, in recent years, attention has been focused oncontainer data centers that can be provided at a short delivery time,have a high equipment expandability, and can be provided by less initialinvestment, and container data centers have begun being operated. Insuch a container data center, power consumed by air-conditioningmachines can be reduced by using the external air to cool down ITdevices.

Also a technique is known for enabling servers to be integrated in ahigh density by omitting a cold aisle for cooling down the air, or aventilation flue within racks in a data center.

Additionally, a technique is known for reducing the volume of coolingair by providing a supply port in a data center for supplying coolingair blown by an air-conditioning machine into the area of a flow passageup to an intake of an exhaust of hot air emitted from an electronicdevice.

Furthermore, a technique is known for improving cooling efficiency byproviding a grille that cools down the air within an accommodation roomfor accommodating IT devices, supplies the cooled air under the floor,and circulates the air within the accommodation room in a data center.

Patent Document 1: Japanese Laid-open Patent Publication No. 2011-191974

Patent Document 2: Japanese Laid-open Patent Publication No. 2011-190967

Patent Document 3 Japanese Laid-open Patent Publication No. 2011-59741

SUMMARY

In one proposal, an information processing device includes a memory anda processor. The memory stores correlation information. The correlationinformation is information that indicates a change in first powerconsumption, which is a total sum of second power consumption of aprocessing unit included in an information processing system and thirdpower consumption of an air-conditioning machine included in theinformation processing system, with respect to a change in a temperatureof the processing unit. The processor determines a target value of thetemperature of the processing unit on the basis of the temperature ofthe processing unit when the first power consumption indicates arelatively low power consumption by referring to the correlationinformation stored in the memory, and outputs a control signal forcontrolling the air-conditioning machine on the basis of the targetvalue.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a configuration of an information processing device;

FIG. 2 is a flowchart illustrating a first air-conditioning machinecontrol process;

FIG. 3 illustrates a configuration of an information processing system;

FIG. 4 illustrates a configuration of racks;

FIG. 5 illustrates a service operation form including the informationprocessing system;

FIG. 6 illustrates a configuration of a server;

FIG. 7 illustrates a relationship between a CPU temperature and powerconsumption of a fan unit;

FIG. 8 illustrates a relationship between a CPU temperature and powerconsumption of a CPU;

FIG. 9 illustrates a CPU temperature and total power consumption;

FIG. 10 is a flowchart illustrating a second air-conditioning machinecontrol process;

FIG. 11 is a flowchart illustrating a first fan revolution numbercontrol process;

FIG. 12 illustrates a change in a CPU temperature in the first fanrevolution number control process;

FIG. 13 is a flowchart illustrating a second fan revolution numbercontrol process;

FIG. 14 illustrates a change in a CPU temperature in the second fanrevolution number control process; and

FIG. 15 illustrates fan placement information.

DESCRIPTION OF EMBODIMENTS

Embodiments are described in detail below with reference to thedrawings.

The above described conventional data center has the following problem.

Air-conditioning machines in a container data center include a coolingdevice that cools down exhaust air warmed by operations of IT devices,an air-conditioning fan that sends the cooled air into an IT deviceroom, and an integral fan that is provided within a housing of a serverand cools down components. The cooling device discharges the air cooleddown at a set temperature on the basis of environment information suchas a temperature, humidity and the like, which are obtained from asensor installed in the periphery of a rack that accommodates a server.Moreover, the server secures the volume of air to cool down componentssuch as a central processing unit (CPU) and the like by operating theintegral fan.

Power consumed by the integral fan of the server sometimes accounts for20 to 40 percent of the power consumed by the entire server, and thepower increases as the number of servers within a data center grows.When the number of servers within the data center grows, a temperatureof exhaust air generated by operations of the servers also rises.Therefore, power consumed by the cooling device that cools down theexhaust air and by air-conditioning fans is also expected to increase.

Such a problem occurs not only in a container data center but also inother information processing systems, such as a large data center,including an air-conditioning machine.

To reduce power consumption of individual servers in a data center, itis effective to employ fanless servers, which are servers that do notinclude an integral fan. By employing fanless servers, power consumed byintegral fans is enabled to be reduced. When fanless servers areemployed, the air cooled down by a cooling device is considered to besent to an IT device room. Therefore, suitable control of the volume ofair of an air-conditioning fan is sought.

FIG. 1 illustrates an example of a configuration of an informationprocessing device (computer) used in an information processing systemsuch as a data center or the like. The information processing device 101illustrated in FIG. 1 includes a storage unit 111 and a control unit112. The storage unit 111 stores correlation information 121. Thecorrelation information 121 is information that indicates a change infirst power consumption, which is a total sum of second powerconsumption of a CPU included in the information processing system andthird power consumption of an air-conditioning machine included in theinformation processing system, with respect to a change in a temperatureof the CPU.

The control unit 112 determines a target value of a temperature of a CPUon the basis of the temperature of the CPU when the first powerconsumption indicates a relatively low power consumption by referring tothe correlation information 121 stored in the storage unit 111, andoutputs a control signal for controlling the air-conditioning machine onthe basis of the target value.

FIG. 2 is a flowchart illustrating an example of an air-conditioningmachine control process executed by the information processing device101 illustrated in FIG. 1. The control unit 112 determines a targetvalue of a CPU temperature on the basis of the CPU temperature when thefirst power consumption indicates relatively low power consumption byreferring to the correlation information 121 (step 201), and outputs acontrol signal for controlling the air-conditioning machine on the basisof the target value (step 202).

With such an air-conditioning machine control process, power consumptionof an information processing system including an air-conditioningmachine is enabled to be prevented from being increased.

FIG. 3 illustrates an example of a configuration of an informationprocessing system such as a data center or the like. The informationprocessing system 301 illustrated in FIG. 3 is, for example, a containerdata center, and includes an IT device room 311 and an air-conditioningroom 312.

In the IT device room 311, a partition board 321, a switchboard 322, anair outlet 323, and racks 324-1 to 324-3 are provided. Each of the racks324-i (i=1, 2, 3) accommodates one or more IT devices such as a server,a network device, a storage device, and the like. The IT device room 311is partitioned by the partition board 321 into a hot aisle 313 to whichan exhaust heat from the IT devices is released, and a cold aisle 314into which cooled air from the air-conditioning room 312 flows.

In the meantime, in the air-conditioning room 312, a damper 331, fanunits 332-1 to 332-3, an air inlet 333, a cooling device 334-1, acooling device 334-2, an air-conditioning control device 335, and asensor 336 are provided. Each of the fan units 332-i (i=1, 2, 3)includes one or more fans.

The air inlet 333 of the air-conditioning room 312 and the air outlet323 of the IT device room 311 are provided with a louver. The externalair, which is the air external to the information processing system, istaken from the air inlet 333 into the air-conditioning room 312, andsent from the fan units 332-1 to 332-3 to the IT device room 311. Thefan units 332-1 to 332-3 are present at positions that are respectivelyopposed to the racks 324-1 to 324-3 within the IT device room 311, andsend the air to a front face of the racks via the cold aisle 314.

The air warmed up by the exhaust heat emitted from the IT devices withinthe racks 324-1 to 324-3 is released from aback face of the racks to thehot aisle 313, and emitted outside the information processing system 301via the air outlet 323.

The sensor 336 is a sensor intended to measure an external temperature(atmospheric temperature) and humidity. The cooling devices 334-1 and334-2 have a function of cooling down and damping the external air takeninto the air-conditioning room 312. For the temperature and the humidityat which the IT devices operate, an upper limit value and a lower limitvalue are respectively decided. A temperature range is, for example, 10degrees Celsius to 35 degrees Celsius, and a humidity range is, forexample, 10 percent to 80 percent.

Accordingly, when the temperature of the external air, which is measuredby the sensor 336, is higher than the upper limit value, the externalair may be cooled down by the cooling device 334-1 and the coolingdevice 334-2, and sent to the IT device room 311. Moreover, when thehumidity of the external air, which is measured by the sensor 336, islower than the lower limit value, the external air may be damped by thecooling device 334-1 and the cooling device 334-2, and sent to the ITdevice room 311. As the cooling device 334-1 and the cooling device334-2, for example, a cooling device of a vaporization type is used.

Alternatively, when the temperature of the external air measured by thesensor 336 is lower than the lower limit value, warm air within the ITdevice room 311 may be taken into the air-conditioning room 312 via thedamper 331, and the external air taken into the air-conditioning room312 will then be mixed with the warm air, and the mixed air sent to theIT device room 311.

The air-conditioning control device 335 is a device that controlsair-conditioning machines such as the damper 331, the fan units 332-1 to332-3, the cooling device 334-1, the cooling device 334-2, the sensor336, and the like. As the air-conditioning control device 335, forexample, a programmable controller is used.

Additionally, a breaker for supplying power to various types of deviceswithin the information processing system 301 is provided within theswitchboard 322. The various types of devices include IT devices, thedamper 331, the fan units 332-1 to 332-3, the cooling device 334-1, thecooling device 334-2, the sensor 336, lighting equipment notillustrated, and the like.

Note that the number of the racks 324 and that of the fan units 332 arenot limited to three, and may be an integer equal to or larger than 1.Also the number of the cooling devices 334 is not limited to two, andmay be an integer equal to or larger than 1.

FIG. 4 illustrates an example of a configuration of the racks 324illustrated in FIG. 3. In the example illustrated in FIG. 4, each of theracks 324-i is able to accommodate IT devices of 42 stages 1U to 42U. Inthe stages 1U to 41U, fanless servers are accommodated. In the stage24U, a switch device is accommodated. Note that, however, the number ofstages of each of the racks is not limited to 42 and may be an integerequal to or larger than 1. Each of the stages may accommodate adifferent IT device. For example, a server having an integral fan may beaccommodated as a replacement for a fanless server.

FIG. 5 illustrates a service operation form including the informationprocessing system 301 illustrated in FIG. 3. A client 501 transmits aprocessing request to servers 511-1 to 511-N (N is an integer equal toor larger than 1) of the information processing system 301 via acommunication network 502 such as the Internet or the like. Each of theservers 511-j (j=1, 2, . . . , N) is a server accommodated by one of theracks 324-1 to 324-3. The server 511-j executes information processingin response to the processing request transmitted from the client 501,and returns a result of the processing to the client 501 via thecommunication network 502.

The servers 511-1 to 511-N and the air-conditioning control device 335are able to communicate with one another via a communication network 521such as a local area network (LAN) or the like. One of the servers 511-1to 511-N operates as the information processing device 101 that isillustrated in FIG. 1 and executes the air-conditioning machine controlprocess. For the sake of convenience, the server 511-1 is hereinafterassumed to operate as the information processing device 101.

In the breaker within the switchboard 322, a power meter 512 isprovided. The power meter 512 measures a total power consumption of theinformation processing system 301, and notifies the air-conditioningcontrol device 335 of the measured value. When a plurality of breakersare provided respectively for a plurality of power distribution systems,one power meter 512 is provided for each of the breakers, and each ofthe power meters 512 notifies the air-conditioning control device 335 ofthe power consumption of each of the power distribution systems.

The sensor 336 measures the temperature and the humidity of the externalair, and notifies the air-conditioning control device 335 of themeasured values. The air-conditioning control device 335 is able tocontrol the damper 331, the fan units 332-1 to 332-3, the cooling device334-1, and the cooling device 334-2 on the basis of the notifiedtemperature and humidity of the external air.

Furthermore, the air-conditioning control device 335 notifies the server511-1 of the information such as the measured temperature of theexternal air, measured power consumption, and the like. The servers511-2 to 511-N notify the server 511-1 of information of their CPUtemperature, CPU load, and the like.

The server 511-1 determines a target value of a CPU temperature byexecuting the air-conditioning machine control process on the basis ofthe notified information, and transmits, to the air-conditioning controldevice 335, a control signal for controlling an air-conditioning machineon the basis of the target value. Then, the air-conditioning controldevice 335 controls the damper 331, the fan units 332-1 to 332-3, thecooling device 334-1, and the cooling device 334-2 in accordance withthe received control signal.

FIG. 6 illustrates an example of a configuration of the server 511illustrated in FIG. 5. The server 511 illustrated in FIG. 6 includes aCPU 601 (processor), a memory 602, a read only memory (ROM) 603, anexternal storage device 604, a baseboard management controller (BMC)605, a network connecting device 606, and a medium driving device 607.These components are interconnected by a bus 608.

The CPU 601 incorporates a temperature sensor that measures a CPUtemperature. The memory 602 is a semiconductor memory such as a randomaccess memory (RAM) or the like. The ROM 603 is a memory that stores aprogram used for processes.

The CPU 601 within the server 511-1 operates as the control unit 112illustrated in FIG. 1 and executes the air-conditioning control machinecontrol process by executing a program with the use of the memory 602.The memory 602 is also available as the storage unit 111 illustrated inFIG. 1.

Additionally, the CPU 601 is able to obtain information of a CPU load byexecuting a management program. As the information of the CPU load, forexample, a CPU usage rate is used. The CPU 601 within the servers 511-2to 511-N notifies the server 511-1 of the obtained information of theCPU load via the network connecting device 606.

The external storage device 604 is, for example, a magnetic disk device,an optical disk device, a magneto-optical disk device, a tape device, orthe like. The external storage device 604 also includes a hard diskdrive. The server 511 is able to store a program and data in theexternal storage device 604, and use the program and the data by loadingthem into the memory 602.

The BMC 605 is a monitoring device that monitors operations of hardwarewithin the server 511, and obtains information of a CPU temperature fromthe temperature sensor within the CPU 601. The BMC 605 within the server511-1 transfers the obtained information of the CPU temperature to theCPU 601.

In the meantime, the BMC 605 within the servers 511-2 to 511-N notifiesthe server 511-1 of the obtained information of the CPU temperature viathe network connecting device 606. The server 511-1 controls theair-conditioning machine to make the notified CPU temperature closer tothe target value of the temperature of the CPU 601.

The network connecting device 606 is a communication interface that isconnected to the communication network 502 and the communication network521 and performs a data conversion accompanying a communication. Theserver 511 is able to receive a program and data from an external devicevia the network connecting device 606, and use the program and the databy loading them into the memory 602.

The medium driving device 607 drives the portable recording medium 611,and accesses recorded contents of the medium. The portable recordingmedium 611 is a memory device, a flexible disk, an optical disk, amagneto-optical disk, or the like. The portable recording medium 611 maybe a compact disk read only memory (CD-ROM), a digital versatile disk(DVD), a flash memory, a universal serial bus (USB) memory, or the like.A user or an operator is able to store a program and data on theportable recording medium 611, and use the program and the data byloading them into the memory 602.

The computer-readable recording medium as described above that stores aprogram and data which are used for the processes includes a physical(non-transitory) recording medium such as the memory 602, the ROM. 603,the external storage device 604, and the portable recording medium 611.

Note that the server 511 does not need to include all the componentsillustrated in FIG. 6. Some of the components may be omitted dependingon an application purpose or a condition. For example, when the server511 does not access the portable recording medium 611, the mediumdriving device 607 may be omitted. Moreover, the number of CPUs 601 andof memories 602 and the like which are included in the server 511 arenot limited to one, and may be an integer equal to or larger than 1.

Away of determining the correlation information 121 illustrated in FIG.1 is described next with reference to FIGS. 7 to 9.

FIG. 7 illustrates a relationship between a temperature at the time ofoperations of a CPU 601 within the server 511 and power consumption of afan unit 332. When the number of revolutions of a fan included in thefan unit 332 is decreased, the temperature of the CPU 601 rises eventhough the power consumption of the fan unit 332 decreases.

FIG. 8 illustrates a relationship between a temperature at the time ofoperations of a CPU 601 within the server 511 and power consumption ofthe CPU 601. When the temperature of the CPU 601 rises, a leak currentwithin the CPU 601 increases. Therefore, the power consumption of theCPU 601 increases even though the CPU operates with the same CPU loadimposed.

As described above, a cause-and-effect relationship is proved to existsuch that the temperature of a CPU 601 rises to increase the powerconsumption of the CPU 601 when the number of revolutions of a fan isdecreased to reduce the power consumption of the information processingsystem 301, which makes the power consumption of the informationprocessing system 301 start to increase.

FIG. 9 illustrates a relationship between a temperature at the time ofoperations of a CPU 601 within the server 511 and a total powerconsumption including the power consumption of the CPU 601 and that of afan unit 332. When the total power consumption is decreased by reducingthe power consumption of the fan unit 332, the temperature of the CPU601 rises. Accordingly, it is expected that the power consumption of theCPU 601 will rise with an increase in a leak current and the total powerconsumption will start to increase at a temperature T1. The total powerconsumption P1 at the temperature T1 corresponds to a minimal value ofthe total power consumption.

Accordingly, by monitoring the total power consumption of theinformation processing system 301 and the temperature of each of theCPUs 601 within each of the servers 511, a change in the total powerconsumption with respect to a change in the temperature of each of theCPUs 601 as illustrated in FIG. 9 is determined, and the determinedchange is available as the correlation information 121.

In this case, a target value of the temperature of the CPU 601 isenabled to be determined on the basis of the temperature of the CPU 601when the total power consumption indicates a relatively low powerconsumption in the correlation information 121. Moreover, by controllingthe number of revolutions of a fan with the use of the target value, thepower consumption of the information processing system 301 is preventedfrom being increased. For example, the temperature T1 corresponding tothe minimal value P1 of the total power consumption of the informationprocessing system 301 is available as the target value of thetemperature of the CPU 601.

FIG. 10 is a flowchart illustrating an example of the air-conditioningmachine control process executed by the control unit 112 within theserver 511-1. The control unit 112 initially accumulates information ofthe CPU temperature and the CPU load of the server 511-1, information ofa CPU temperature and a CPU load, which are reported from each of theservers 511-2 to 511-N, and information reported from theair-conditioning control device 335 in association with each date andtime (step 1001). The information reported from the air-conditioningcontrol device 335 includes a measurement value of power consumption ofeach power distribution system, which is measured by the power meter512, and a measurement value of the temperature of the external air,which is measured by the sensor 336.

Next, the control unit 112 classifies the power consumptions and the CPUtemperatures of corresponding power distribution systems by a numericalvalue range of the temperature of the external air and that of the CPUload, and determines the correlation information 121 by using the powerconsumptions and the CPU temperatures which are classified respectivelyby the numerical value ranges (step 1002). Then, the control unit 112stores, in the storage unit 111, a plurality of pieces of thecorrelation information 121 which correspond to the plurality ofnumerical value ranges of the temperature of the external air and theCPU load.

For example, the following method is conceivable as a way of determiningthe correlation information 121.

(1) A total sum of power consumptions of the power distribution systemsis obtained as a total power consumption. Then, the correlationinformation 121 that indicates a relationship between the total powerconsumption of the information processing system 301 and a CPUtemperature is determined for each of the CPUs 601 by making anassociation between a total power consumption for each date and time andthe CPU temperature of each of the CPUs 601.

(2) A total sum of power consumptions of the power distribution systemsis obtained as the total power consumption, and an average value of CPUtemperatures of the plurality of CPUs 601 within each server 511 isobtained. Then, the correlation information 121 that indicates arelationship between the total power consumption of the informationprocessing system 301 and a CPU temperature is determined for each ofthe servers 511 by making an association between the total powerconsumption and the average value of the CPU temperatures for each dateand time.

(3) A total sum of power consumptions of the power distribution systemsis obtained as a total power consumption, and an average value of theCPU temperatures of the plurality of CPUs 601 within the informationprocessing system 301 is obtained. Then, the correlation information 121that indicates a relationship between the total power consumption of theinformation processing system 301 and an average value of the CPUtemperatures of all the CPUs 601 is determined by making an associationbetween the total power consumption and the average value of the CPUtemperatures of all the CPUs 601 for each date and time.

Next, the control unit 112 determines a CPU temperature corresponding tothe minimal value of the total power consumption on the basis of thecorrelation information 121 corresponding to numerical value ranges towhich the current temperature of the external air and the current valueof the CPU load respectively belong, and chooses the determined CPUtemperature as the target value (step 1003).

When the correlation information 121 is determined for each of the CPUs601, the CPU temperature corresponding to the minimal value of the totalpower consumption in the correlation information 121 of each of the CPUs601 is chosen as the target value of the CPU temperature of thecorresponding CPU 601. Moreover, when the correlation information 121 isdetermined for each of the servers 511, the CPU temperaturecorresponding to the minimal value of the total power consumption in thecorrelation information 121 of each of the servers 511 is chosen as thetarget value of the CPU temperature of the corresponding server 511.

Then, the control unit 112 controls the number of revolutions of the fanincluded in the fan unit 332 on the basis of the chosen target value(step 1004).

When the information processing system 301 is installed in anenvironment where the temperature of the external air falls within acertain range, there is no need to determine the correlation information121 for each numerical range of the temperature of the external air.Accordingly, the air-conditioning control device 335 does not need tonotify the server 511-1 of the temperature of the external air, which ismeasured by the sensor 336. In this case, the correlation information121 corresponding to the current CPU load is used in step 1003.

Additionally, when the CPU load falls within a certain range, there isno need to determine the correlation information 121 for each numericalvalue range of the CPU load. Accordingly, the server 511-1 does not needto obtain a CPU load, and the servers 511-2 to 511-N do not need tonotify the server 511-1 of their CPU load. In this case, the correlationinformation 121 corresponding to the current temperature of the externalair is used in step 1003.

Furthermore, when the correlation information 121 is determine with asimulation, there is no need to accumulate actual total powerconsumptions and CPU temperatures in all cases. Accordingly, theair-conditioning control device 335 does not need to notify the server511-1 of the power consumption of each of the power distributionsystems, which is measured by the power meter 512. Moreover, the server511-1 does not need to obtain a CPU temperature, and the servers 511-2to 511-N do not need to notify the server 511-1 of their CPUtemperature.

FIG. 11 is a flowchart illustrating an example of the fan revolutionnumber control process executed in step 1004 illustrated in FIG. 10. Thecontrol unit 112 initially transmits, to the air-conditioning controldevice 335, a control signal for controlling the number of revolutionsof a fan to be minimized (step 1101), and makes a comparison between aCPU temperature and a target value at specified time intervals (step1102).

To cool down the CPU 601 on which the highest CPU load is imposed withinthe information processing system 301 with a high priority, a comparisonis made, for example, between the CPU temperature of the CPU on whichthe highest CPU load is currently imposed and a target value. At thistime, when the correlation information 121 is determine for each of theCPUs 601, the target value of the CPU 601 on which the highest CPU loadis imposed is used for the comparison. Alternatively, when thecorrelation information 121 is determine for each of the servers 511,the target value of the server 511 that includes the CPU 601 on whichthe highest CPU load is imposed is used for the comparison. Moreover,when the correlation information 121 is determine for all the CPUs 601within the information processing system 301, a target value for all theCPUs 601 is used for the comparison.

Note that the comparison may be made between the target value and theCPU temperature of the CPU 601 in which the CPU temperature is currentlythe highest as a replacement for the CPU 601 in which the highest CPUload is currently imposed.

When the CPU temperature is higher than the target value (“YES” in step1102), the control unit 112 transmits, to the air-conditioning controldevice 335, a control signal for increasing the number of revolutions ofthe fan by a specified value in order to cool down the CPU 601 (step1103). Then, the control unit 112 checks whether the number ofrevolutions of the fan has reached a maximum value (step 1104). When thenumber of revolutions of the fan has not reached the maximum value (“NO”in step 1104), the control unit 112 repeats the processes in and afterstep 1102.

In the meantime, when the CPU temperature is equal to or lower than thetarget value (“NO” in step 1102), the control unit 112 transmits, to theair-conditioning control device 335, a control signal for decreasing thenumber of revolutions of the fan by a specified value in order to reducethe power consumption (step 1108). Then, the control unit 112 repeatsthe processes in and after step 1102. By setting the increment of thenumber of revolutions of the fan in step 1103 to a value larger than thedecrement of the number of revolutions of the fan in step 1108, the CPU601 is enabled to be quickly cooled down.

When the number of revolutions of the fan reaches the maximum value(“YES” in step 1104), the control unit 112 makes a comparison betweenthe CPU temperature and the target value (step 1106) after the controlunit 112 waits for a certain length of time (step 1105). When the CPUtemperature is equal to or lower than the target value (“NO” in step1106), the control unit 112 repeats the processes in and after step1102.

In the meantime, when the CPU temperature is higher than the targetvalue (“YES” in step 1102), the control unit 112 performs throttling forthe CPU 601 in which the CPU temperature is higher than the target value(step 1107). Then, the control unit 112 repeats the processes in andafter step 1102.

In the throttling performed for the CPU 601 in step 1107, an operatingfrequency of the CPU 601 is restricted. As a result, an operatingtemperature of the CPU 601 is expected to drop. Thereafter, when the CPUtemperature drops to the target value or lower (“NO” in step 1102), thecontrol unit 112 decreases the number of revolutions of the fan in step1108, and cancels the throttling.

FIG. 12 illustrates a change in the CPU temperature in such a fanrevolution number control process. When the air-conditioning controldevice 335 controls the number of revolutions of a fan with a PulseWidth Modulation (PWM) control, the air-conditioning control device 335outputs a PWM signal to the fan unit 332. In this case, the control unit112 outputs a control signal for designating a duty ratio of the PWMsignal as the control signal for controlling the number of revolutionsof the fan.

In the example illustrated in FIG. 12, the target value of the CPUtemperature is 70 degrees Celsius, the increment of the duty ratio,which designates the increment of the number of revolutions of the fanin step 1103, is 20 percent, and the decrement of the duty ratio, whichdesignates the decrement of the number of revolutions of the fan in step1108, is 10 percent. A polygonal line 1201 represents a time change ofthe duty ratio, whereas a polygonal line 1202 represents a time changeof the CPU temperature.

The control unit 112 initially controls the power consumption of the fanunit 332 to be minimized by transmitting, to the air-conditioningcontrol device 335, a control signal of the duty ratio of 0 percent,which designates the minimum value of the number of revolutions of thefan. When the CPU temperature exceeds 70 degrees Celsius at a time t1,the control unit thereafter increments the duty ratio by 20 percent atspecified time intervals. When the duty ratio reaches 100 percent, whichdesignates the maximum value of the number of revolutions of the fan,the control unit 112 waits for a certain length of time until a time t2.When the CPU temperature drops to 70 degrees Celsius or lower at thetime t2, the control unit 112 thereafter decrements the duty ratio by 10percent at specified time intervals.

Note that the increment and the decrement of the duty ratio may bechanged on the basis of at least one of the temperature of the externalair and a CPU load. The length of time to cool down the CPU 601increases as the temperature of the external air rises. Therefore, it isdesirable to change the increment and the decrement of the duty ratio toa larger value. Similarly, the length of time to cool down the CPU 601increases as the CPU load becomes heavier. Therefore, it is desirable tochange the increment and the decrement of the duty ratio to a largervalue.

With such a fan revolution number control process, the number ofrevolutions of the fan is controlled to make the CPU temperature closerto the target value in all cases. As a result, the power consumption ofthe fan unit 332 is prevented from being increased.

FIG. 13 is a flowchart illustrating another example of the fanrevolution number control process executed in step 1004 of FIG. 10. Thecontrol unit 112 initially performs a Proportional-Integral-Differential(PID) control for making a CPU temperature closer to a target value, andtransmits, to the air-conditioning control device 335, a control signalfor designating the number of revolutions of a fan (step 1301). In step1301, the CPU 601 on which the highest CPU load is currently beingimposed or in which the CPU temperature is currently the highest isselected as a target of a temperature control.

Next, the control unit 112 checks whether the number of revolutions ofthe fan has reached a maximum value (step 1302). When the number ofrevolutions of the fan has not reached the maximum value (“NO” in step1302), the control unit 112 repeats the processes in and after step1301.

In the meantime, when the number of revolutions of the fan reaches themaximum value (“YES” in step 1302), the control unit 112 makes acomparison between the CPU temperature and the target value (step 1303).When the CPU temperature is equal to or lower than the target value(“NO” in step 1303), the control unit 112 repeats the processes in andafter step 1301.

In the meantime, when the CPU temperature is higher than the targetvalue (“YES” in step 1303), the control unit 112 performs throttling forthe CPU 601 in which the CPU temperature is higher than the target value(step 1304). Then, the control unit 112 repeats the processes in andafter step 1301. Thereafter, when the CPU temperature drops to thetarget value or lower in step 1301, the control unit 112 resets thenumber of revolutions of the fan, and cancels the throttling.

FIG. 14 illustrates a change in a CPU temperature in such a fanrevolution number control process. In the example illustrated in FIG.14, a target value of the CPU temperature is 70 degrees Celsius, and apolygonal line 1401 represents a time change of a duty ratio, whereas apolygonal line 1402 represents a time change in the CPU temperature.

The control unit 112 initially transmits a control signal of the dutyratio of 0 percent to the air-conditioning control device 335 to controlthe power consumption of the fan unit 332 to be minimized. Thereafter,the control unit 112 increases the duty ratio as the CPU temperaturerises, and decreases the duty ratio when the CPU temperature starts todrop.

With such a fan revolution number control process, the number ofrevolutions of the fan is controlled to make the CPU temperature closerto the target value in all cases. As a result, the power consumption ofthe fan unit 332 is prevented from being increased.

The flowcharts illustrated in FIGS. 10, 11, and 13 are merely examples,and some of the processes may be omitted or changed depending on aconfiguration or a condition of the information processing system 301.For example, when there is a low possibility that the number ofrevolutions of the fan will reach the maximum value in the fanrevolution number control process illustrated in FIG. 11, the processesin steps 1104 to 1107 may be omitted. Similarly, when there is a lowpossibility that the number of revolutions of the fan will reach themaximum value in the fan revolution number control process illustratedin FIG. 13, the processes in steps 1302 to 1304 may be omitted.

Additionally, in step 1004 illustrated in FIG. 10, the operations of thedamper 331, the cooling device 334-1 or the cooling device 334-2 may becontrolled instead of controlling the number of revolutions of the fanof the fan unit 332.

Incidentally, there is no need to control the numbers of revolutions ofthe fans of the fan units 332-1 to 332-3 to become equal in step 1004illustrated in FIG. 10, and it is sufficient to enable the CPU 601 onwhich the highest CPU load is currently being imposed or in which theCPU temperature is currently the highest to be selectively cooled down.Accordingly, it is conceivable to perform a control for increasing thenumber of revolutions of the fan of the fan unit 332 present at aposition opposed to the rack 324 including the CPU 601 desired to becooled down without changing the number of revolutions of fans of theother fan units 332.

FIG. 15 illustrates an example of fan placement information used in sucha fan revolution number control process. The fan placement informationillustrated in FIG. 15 includes entries such as a fan unit ID 1501, arack ID 1502, an intra-rack position 1503, and a device ID 1504, and isstored in the storage unit 111.

The fan unit ID 1501 represents identification information of the fanunit 332. F1 to F3 are identification information of the fan units 332-1to 332-3, respectively. The rack ID 1502 represents identificationinformation of the rack 324. R1 to R3 are identification information ofthe racks 324-1 to 324-3, respectively. By respectively associating F1to F3 with R1 to R3, it can be seen that the fan units 332-1 to 332-3are installed at positions that are respectively opposed to the racks324-1 to 324-3.

The intra-rack position 1503 represents each of the stages 1U to 42Uwithin each of the racks 324-i illustrated in FIG. 4, and the device ID504 represents identification information of a device accommodated ineach of the stages 1U to 42U. SV1 to SV123 are identificationinformation of the servers 511, whereas SW1 to SW3 are identificationinformation of the switch devices.

In the storage unit 111, configuration information that represents anassociation between the identification information of each of theservers 511 and that of the CPU 601 included in the corresponding server511 is also stored. This configuration information and the fan placementinformation serve as position information that represents relationshipsbetween positions of the plurality of CPUs 601 and those of a pluralityof fans. The control unit 112 is able to identify a fan unit 332 presentat a position opposed to a rack 324 including the CPU 601 desired to becooled down on the basis of the configuration information and the fanplacement information.

In this case, insteps 1101, 1103 and 1108 illustrated in FIG. 11, andstep 1301 illustrated in FIG. 13, the control unit 112 identifies thefan unit 332 corresponding to the CPU 601 for which the temperature isto be controlled. Then, the control unit 112 transmits, to theair-conditioning control device 335, a control signal for controllingthe number of revolutions of the fan of the identified fan unit 332.

For example, when the CPU temperature of the CPU 601 included in therack 324-1 exceeds the target value and those of the CPUs 601 includedin the racks 324-2 and 324-3 are equal to or lower than the targetvalue, the control unit 112 performs a control for increasing only thenumber of revolutions of the fan of the fan unit 332-1.

With such a fan revolution number control process, the power consumptionof the fan unit 332 corresponding to the rack 324 that does not includethe CPU 601 for which the temperature is to be controlled does notincrease. As a result, the power consumption is enabled to be preventedfrom being uselessly increased.

When the fan unit 332 includes a plurality of fans, the number ofrevolutions may be controlled for each of the fans by using fanplacement information including an association between a position ofeach of the fans and a position within a rack.

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat the various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. A controlling method, comprising: determining atarget value of a temperature of a processing unit included in aninformation processing system when first power consumption, which is atotal sum of second power consumption of the processing unit and thirdpower consumption of an air-conditioning machine included in theinformation processing system, indicates a relatively low powerconsumption by using correlation information corresponding to at leastone of a measured temperature and a measured load among a plurality ofpieces of correlation information corresponding to a plurality of rangesof at least one of a temperature outside the information processingsystem and a load of the processing unit, each of the plurality ofpieces of correlation information indicating a change in the first powerconsumption with respect to a change in the temperature of theprocessing unit; and controlling the air-conditioning machine on thebasis of the target value.
 2. The information processing device,comprising a memory configured to store a plurality of pieces ofcorrelation information corresponding to a plurality of ranges of atleast one of a temperature outside an information processing system anda load of a processing unit included in the information processingsystem, each of the plurality of pieces of correlation informationindicating a change in first power consumption, which is a total sum ofsecond power consumption of the processing unit and third powerconsumption of an air-conditioning machine included in the informationprocessing system, with respect to a change in a temperature of theprocessing unit; and a processor configured to determine a target valueof the temperature of the processing unit based on the temperature ofthe processing unit when the first power consumption indicates arelatively low power consumption by using correlation informationcorresponding to at least one of a measured temperature and a measuredload among the plurality of pieces of correlation information stored inthe memory, and to output a control signal for controlling theair-conditioning machine based on the target value.
 3. The informationprocessing device according to claim 2, wherein the processor determinesthe correlation information by using a measured value of the first powerconsumption and a measured value of the temperature of the processingunit, and stores the determined correlation information in the memory.4. The information processing device according to claim 2, wherein theprocessor determines the temperature of the processing unit with whichthe first power consumption is reduced, as the target value, and outputsthe control signal for controlling the air-conditioning machine to makethe temperature of the processing unit closer to the target value. 5.The information processing device according to claim 2, wherein theprocessor outputs the control signal for controlling the number ofrevolutions of a fan included in the air-conditioning machine.
 6. Theinformation processing device according to claim 5, wherein the memoryfurther stores position information that indicates a relationshipbetween each position of a plurality of processing units including theprocessing unit and each position of a plurality of fans included in theair-conditioning machine, and the processor outputs the control signalfor controlling the number of revolutions of a fan present at a positionwhich corresponds to a position of the processing unit included in thecorrelation information, on the basis of the position information. 7.The information processing device according to claim 2, wherein thesecond power consumption includes a total sum of power consumptions of aplurality of processing units including the processing unit.
 8. Anon-transitory computer-readable recording medium having stored thereina program for causing a computer to execute a process comprising:determining a target value of a temperature of a processing unitincluded in an information processing system when first powerconsumption, which is a total sum of second power consumption of theprocessing unit and third power consumption of an air-conditioningmachine included in the information processing system, indicates arelatively low power consumption by using correlation informationcorresponding to at least one of a measured temperature and a measuredload among a plurality of pieces of correlation informationcorresponding to a plurality of ranges of at least one of a temperatureoutside the information processing system and a load of the processingunit, each of the plurality of pieces of correlation informationindicating a change in the first power consumption with respect to achange in the temperature of the processing unit; and outputting acontrol signal for controlling the air-conditioning machine on the basisof the target value.